Catalyst for the preparation of unsaturated aldehydes



United States Patent 4 Claims ABSTRACT OF THE DISCLOSURE Improved catalysts for use in the oxidation of olefins comprising copper phosphate, TeO and HR O on a refractory supported are present herein.

This is a division of application Ser. No. 338,571, filed Jan. 20, 1964, now Patent No. 3,369,049.

This invention relates to a method for preparing acrolein or methacrolein by the catalytic oxidation of propylene or isobutylene in the presence of a catalyst comprising a copper phosphate, a tellurium compound and a rhenium compound at elevated temperatures, and more particularly pertains to a method of oxidizing propylene or isobutylene to acrolein or methacrolein, respectively, by passing a mixture of the olefin and an oxygen containing gas, with or without water vapor, through a catalyst bed at a temperature of about 300500 0, wherein the catalyst is a mixture of a copper phosphate, particularly copper pyrophosphate, an inorganic oxygen containing tellurium compound, such as tellerium oxide and a rhenium compound such as rhenium oxide or perrhenic acid. The ratio of copper pyrophosphate to tellurium to rhenium can be 100: 3021-10. This can be written empirically as in which P is present as a phosphate.

It is known that propylene can be oxidized to acrolein with copper containing catalysts, but the conversion of the propylene and yield of acrolein are quite low, so that the efficiency is also low. The catalytic oxidation of isobutylene to methacrolein is usually more difiicult because .of the lack of selectivity of the catalysts normally used for the oxidation of propylene. The presence of two methyl groups adjacent to the double bonds in isobutylene makes catalytic conversion of the olefin to methacrolein quite diflicnlt. It is therefore unusual to find a catalyst which has approximately the same efiiciency for oxidizing both olefins mentioned above to the corresponding aldehydes, and which converts isobutylene at a lower temperature than propylene. The preferred temperature for preparing acrolein is 420-475 C. and that for methacrolein is 325-450 C.

With the catalysts of this invention it is possible to obtain efficiencies of up to 61.3 for acrolein and up to 58.3 for methacrolein.

Reactants The only essential reactants are oxygen or an oxygen containing gas mixed with an inert gas. The source of oxygen can be relatively pure oxygen, air or a mixture of oxygen diluted with nitrogen so that it contains more than 21% oxygen. Oxygen can also be diluted with other inert gases such as neon, krypton, xenon or helium.

The olefin can be propylene or isobutylene. For the Patented Jan. 21, 1969 purpose of this invention these olefins can be defined by the generic formula CHaC=CHa The olefins need not be pure. They can contain appreciable amounts of saturated alkanes or other hydrocarbons without interference with the main reaction, except for the consumption of some oxygen due to oxidation of a portion of the hydrocarbon contaminants.

Water vapor is not an essential ingredient for the reaction, but it does seem to improve yields of the desired aldehyde at any given temperature and it may also act as a heat absorbing medium which tends to aid in temperature control of the reaction.

The ratios of reactants can vary between 1-3 mols oxygen and 0-7 mols water vapor per mol of olefin.

The catalyst The catalyst is a mixture of a copper phosphate which can be Cu (PO Cu P O, or a copper polyphosphate, such as Cu (PO O with tellurium oxide and a rhenium oxide which can be perrhenic acid or R6207. The molar ratio of ingredients can vary between about 100 for a phosphate, 10-30 for TeO and 1-10 for HReO, or a corresponding amount of Re O Catalyst preparation The catalyst can be prepared by several procedures and it can be supported or unsupported.

For fixed bed reactions the catalyst of 1'0-18 U.S. sieve size is preferred and for fluid bed reactions a US. sieve size of -325 mesh is preferred.

Method I 34.1 g. CuCl -2H O were dissolved in water.

1.6 g. TeO were added to the CuCl solution.

1 g. of HReO dissolved in water was added to the CuCl -TeO mixture.

23.3 g. of H PO were added to the mixture of the above ingredients.

Then 247.8 of a microspheroidal colloidal silica dispersion in water, containing 30-35% by weight SiO were added to the remaining ingredients. After thorough stirring, the mixture was evaporated to dryness on a steam bath and thereafter baked at 400 C. for about 16 hours. If desired, drying can be effected by a spray-drying tech- ,nique. The catalyst was then cooled, crushed and screened to the desired sizes.

Method II In this procedure the TeO was dissolved in concentrated HCl to form a homogeneous mixture prior to the addition of the H PO Otherwise the steps are the same as in Method 1.

Method III Dry, particulate Cu P O- TeO and Re O are blended and ground in a ball mill to the desired fineness and screened. If a support is desired it can be added to the ball mill with the remaining ingredients.

Method IV A paste of Cu P O or other copper phosphate is first prepared, dry TeO and Re O or HReO, are added thereto in the required amounts. The support can be blended with the paste, then dried and baked, as indicated above.

The supports are preferably finely divided refractory materials with low porosity. Suitable supports include silicic materials such as colloidal silica, kieselguhr, clay,

diatomaceous earth, alumina, aluminum phosphate, zirconium oxide, and silicon carbide.

The most preferred supports are colloidal silica and diatomaceous earth.

Reaction conditions The reaction is carried out at a temperature of from about 300500 C. and preferably between about 330- 480 C. The best reaction temperature for converting propylene to acrolein is somewhat higher than that for reaction conditions were substantially the same as those of run 1 above. The propylene conversion was 41.7% and the acrolein yield was 56.1 with an efficiency of 23.4%. In another comparative test a catalyst consisting of 25 mols Cu P O and 1 mol HReO was used, with the same feed ratio described immediately above. The reaction temperature was 460 C. The propylene conversion was 41.5%, acrolein yield was 41.5% for an etficiency of 17.2%. When Cu P O alone was used as the catalyst, using the feed mixture described immediately above and a oxidizing isobutylene to methacrolein, but both aldehydes l reaction temperature f 460 C l 9 4% f the lare p p In most deslrable ywlds and efiiclencles n ene was converted, with a 65.9% yield of acrolein, thus the range of 330450 C. for methacrolein and 420- h i an efl'iciency f 6,24%, 480 C. for acrolein.

The contact time can range between about 2 to about EXAMPLE H E but g' 3 f 2 In this example the catalyst was composed of a molar i e f P ratio of 50 Cu P O s T50 and 2 HReO on 620 mols out 6 e reactapts an out 8 reagtlon of SiO The reaction mixture consisted of 1.1 mols of i j i gg crmca It can range mm oxygen, supplied as air, and 4.4 mols of water vapor per atmosp er to out mol of propylene. The reaction was carried out at 425 C. EXAMPLE I in the reactor described above. The cold contact time was In 40 of a by 5:1 .5552335 53333333252.33 method I, having a molar ratio of 50 Cu P O 5 TeO y 0 y and 2 HReO on 620 mols colloidal silica, were placed EXAMPLE III in a high silica (Vycor) tube reactor 6 in. long and 22 mm. OD. The reactor was electrically heated by three coils, A series of runs was made using several ratios of cataone of which extended along the entire length of the relyst ingredients and varying ratios of oxygen to propylene actor and each of the other two coils extended about 50% and water vapor to propylene. of the reactor length. The reactor was preheated to about The reaction conditions of each run and other pertinent 280-300 C. and then steam at a temperature of about data are recorded in the following table:

Catalyst Mol percent Contact O2/C3H5 H1O/C5H6 Temp, C. Eificiency CU2P207 T001 MReO S10: time, sec. Propylene Acrolein conversion yield 15 10 620 11.4 2.1 3.6 450 91.7 66.9 61.3 15 1 310 10. 5 2. 5 4. 5 420 86.3 67.8 58. 5 2o 1 1, 240 11 1. 1 4.3 445 76. 5 70. 1 53. 5 15 1 620 12. 5 2. 5 3. 6 420 61. 4 83.0 51.0 10 1 620 9. 3 2. 1 4. 3 440 70. 6 72. 6 51. 2 5 2 620 18.3 2. 1 5. 1 430 75. 6 60. 7 45. 9 5 1 620 14 2. 2 4. 5 435 57. 4 63. 5 42. 3 10 1 1. 240 9. 6 2. 1 3. 7 460 55. 0 75.5 41. 5 30 1 1, 240 9. 3 1. 5 4. 3 450 54. 9 68. 6 37. 7 15 1 620 12. 5 2. 5 3. 6 420 61. 4 s3. 0 51. 6 15 1 310 10. 5 2. 5 4. 5 420 86. 3 67. 8 5s. 5 15 1 155 11.0 1. 5 4. 5 440 41.4 91. 0 37. 7

The catalyst shows the molar ratios of ingredients used in its preparation. The contact time is cold contact time.

o 250 C. was adm1tted through one opening in the reactor. EXAMPLE IV The requisite amount of propylene was blended with the steam just prior to entry into the reactor and oxygen (supplied as air) in the required amount was fed into the reactor through a separate entry port.

The reactor temperature was then raised to the temperature indicated in the table of data below. The contact time is cold contact time, the hot contact time is about 40% of the cold contact time listed.

The effluent gases were run through a condenser. The uncondensed gases were passed directly through a vapor phase chromatograph (Perkin-Elmer 154) and analyzed. The condensed liquids were weighed and then vaporized and passed through a vapor phase chromatograph for analysis.

The data obtained in several runs are tabulated below:

EXAMPLE V The catalyst for this run was composed of 50 CU2P207, TeO 1 HReO on 620 mols of ZrO The procedure was the same as already described. The 0 Contact Mol Mol Mol O2/C3Hg HzO/C H time, Temp., Percent Percent Percent see. C. Conver- Yield Efficiency sion, C 113 Acrolein For comparative purposes a mixture of 1.1 mols oxygen (supplied as air) and 4.4 mols of water vapor per mol of propylene was fed into the reactor containing a catalyst C H ratio was 1.1, H O/C H was 4.3, cold contact time was 11.2 seconds and the reaction temperature was 450 C. This catalyst converted 53.2% of the propylene, with a composed of 10 mols Cu P O and 1 mol of TeO The 75 yield of acrolein for an efficiency of 37.2%.

EXAMPLE VI Forty ml. of a catalyst comprising 50 mols 01 F 0 6 50 Cu P O 5 T e0 and 2 HReO, on 620 mols of SiO The data, tabulated below show results obtained with several oxygen-isobutylene ratios:

Contact Mol per- Mol per- M01 per- Oz/CAH 1120/0 11; time, Temp, cent concent yield cent efiici sec. 0. version methaency 0 H; crolein TeO 1 HReO, impregnated on 6 20 mols of a micro- Iclaim:

spheroidal colloidal silica support were placed in the re actor described in Example I. A feed containing a molar ratio of one mol of isobutylene, 2 mols of oxygen, supplied as air, and 4.1 mols of water vapor was passed through a fixed bed of the catalyst at a rate to provide a cold contact time of 945 seconds. At 330 C., 93.6% of the isobutylene fed was converted, to yield 56.8% methacrolein, for an efliciency of 53.2%.

EXAMPLE VII The catalyst of this example had a molar ratio of 50 OllzPzOq, 'TeO l HReO on 310 mole of a microspheroidal colloidal silica. The feed contained a molar ratio of one mol isobutylene, 1.5 mol of oxygen, supplied as air, and 4.1 mols of water vapor. The feed rate was regulated to provide a cold contact time of 27.5 seconds. At 360 C. all the isobutylene in the feed was converted, to yield 58.3% methacrolein. The reactor was then described in Example I and 40 ml. of catalyst were used in a fixed bed.

EXAMPLE VIII The catalyst for this series of runs had a molar ratio of 1. A composition comprising, on a molar basis: (a) 100 mols of a copper phosphate,

15 (b) 10-30 mols T602,

(c) 1-l0 mols HReO on a refractory support. 2. The composition of claim 1 in which the support is a silicic material.

3. The composition of claim 1 in which the copper phosphate is C11 P O and the support is a microspheroidal colloidal silioa.

4. The composition of claim 1 in which the amount of HReO, is l-2 anols.

References Cited UNITED STATES PATENTS 3,301,906 1/ 1967 Besozzi 260-604 3,274,255 9/1966 Brill 260-604 DANIEL E. WYMAN, Primary Examiner.

P. M. FRENCH, Assistant Examiner.

US. Cl. X.R. 2 52-439 Egg? UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, +23 ,331 Dated January 21, 1969 inventor) Jamal S. Eden It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 18, for "supported" read --support--. '1

Column 2, line 22, for "Cu (PO O read --Cu gpo b Column A, in the table, th rd column, for "MReOZ e --HReO column A, line 60, after "011 1 0 insert --l5--.

SIGNED AND SEALED MAR 3 11970 Edwardui'lemhmlr.

. Hm! 8. mm, JR

Au 5 Omar Oommissioner of Patents 

